The present invention relates to certain liquid crystalline polyester siloxanes resulting from the condensation of tetraorganodisiloxane bisbenzoic acid and parahydroxybenzoic acid with particular dihydric phenols such as biphenol or hydroquinone and, in particular instances, in further combination with terephthalic acid.
Prior to the present invention, certain polyestersiloxanes were prepared from 4,4'-(1,1,3,3-tetramethyl-1,3-disiloxanediyl)bis(benzoic acid) as shown by D. W. Lewis and G. C. Gainer, Journal of American Chemical Society, 74, 2931 (1952). In copending application Ser. No. [RD-18734], 4,4'-(1,1,3,3-tetramethyl-1,3-disiloxanediyl)bis(benzoic acid) included within the formula ##STR1## where R is the same or different C.sub.(l-13) monovalent hydrocarbon radical, or C.sub.(1-13) monovalent hydrocarbon radical substituted with radicals inert during condensation can be condensed with various dihydric phenols along with other aromatic organodicarboxylic acids to produce a variety of polyester-siloxanes.
It has now been discovered that if the tetraorganodisiloxane bisbenzoic acid of formula (1) is condensed with parahydroxybenzoic acid, and particular dihydric phenols such as diphenol, hydroquinone or 4,4'-dihydroxydiphenyl ether, the resulting polyester siloxanes exhibit liquid crystalline properties. As a result, the liquid crystalline polyester siloxanes of the present invention exhibit lower processing temperatures and improved strength after being injection molded into particular shapes in various applications.